Not in our backyard: Spectroscopic support for the clash z = 11 candidate Macs 0647-jd

Nor Pirzkal, Dan Coe, Brenda L. Frye, Gabriel Brammer, John Moustakas, Barry Rothberg, Thomas J. Broadhurst, Rychard Bouwens, Larry Bradley, Arjen Van Der Wel, Daniel D. Kelson, Megan Donahue, Adi Zitrin, Leonidas Moustakas, Elizabeth Barker

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


We report on our first set of spectroscopic Hubble Space Telescope observations of the candidate galaxy, which is strongly lensed by the MACSJ 0647.7+7015 galaxy cluster. The three lensed images are faint and we show that these early slitless grism observations are of sufficient depth to investigate whether this high-redshift candidate, identified by its strong photometric break at , could possibly be an emission line galaxy at a much lower redshift. While such an interloper would imply the existence of a rather peculiar object, we show here that such strong emission lines would clearly have been detected. Comparing realistic, two-dimensional simulations to these new observations, we would expect the necessary emission lines to be detected at , though we see no evidence for such lines in the dispersed data of any of the three lensed images. We therefore exclude that this object could be a low-redshift emission line interloper, which significantly increases the likelihood of this candidate being a bona fide galaxy.

Original languageEnglish
Article number11
JournalAstrophysical Journal
Issue number1
StatePublished - 1 May 2015
Externally publishedYes


  • galaxies: high-redshift
  • techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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